We plan a three-day symposium to bring together leading researchers in the fields of cognitive development, visual perception, language acquisition, developmental neuroscience, and computational modeling to address key questions about the nature of category representations and the mechanisms that produce them. Investigators will be asked to address the question of how children build object categories from the ground up, beginning with the basic architecture of the brain and with the constraints of biases that provide the foundation of early perceptual experience. These developments will be considered in view of subsequent growth of categorical and semantic abilities. Research will be presented that examines three interrelated themes: (1) fundamental processes by which children are able to individuate and categorize objects and their physical properties, (2) the contribution of language in the selection of features relevant for object categorization, and (3) high-level cognitive processes that guide the formation of coherent systems of category knowledge. The aim is to encourage the exchange of ideas, to synthesize the fields progress, and to call attention to areas where additional empirical studies are needed. The results of the symposium will be published as the 32nd in the series of Carnegie Cognition Symposium volumes.